Designing new organic materials to control magnetism using electric fields

Abstract

The development of magnetoelectric materials, where magnetic and electric properties are coupled, has recently attracted significant attention due to their promising technological applications. This work explores the electric-field control of magnetic exchange interactions in fully organic diradicals composed of two stable radicals (trioxotriangulene radicals) connected by a dipolar linker, where the magnetoelectric response is tuned by modifying the linker dipole moment. Two new linkers, dicyanobenzene and dicyanoquinoxaline, are compared with a previously investigated reference system, a difluorobenzene-linked diradical, using density functional theory calculations. All molecular structures are obtained from DFT-based geometry optimizations employing the PBE0 exchange–correlation functional together with the 6-311G(d,p) basis set as implemented in the Gaussian09 package. The results show that increasing the dipole moment enhances the coupling between the electric field and the molecule, leading to larger changes in the torsional angle θ and, consequently, in the exchange coupling J. Among the systems studied, the dicyanoquinoxaline-linked diradical exhibits the strongest response, particularly in the out-of-plane configuration, which provides smooth and stable magnetoelectric tuning. These findings identify dicyanoquinoxaline as a promising linker for achieving efficient electric-field control of magnetism in organic systems.